The userland version is also from the original author of WireGuard and not that bad actually. I'm currently running it in an OPNsense box to serve our internet

The userland version is also from the original author of WireGuard and not that bad actually. I'm currently running it in an OPNsense box to serve our internet needs. I have a connection that without VPN can push through about 400-800 Mbps, and when I put the VPN on for all traffic, I can still push 400-800 Mbps through my connection. The in-kernel version can do the same with less CPU usage, and can probably drive multi-gigabit connections without any trouble.